Liquid purification or separation – Processes – Chemical treatment
Reexamination Certificate
2001-01-31
2002-07-16
Hoey, Betsey Morrison (Department: 1724)
Liquid purification or separation
Processes
Chemical treatment
C210S757000, C210S758000, C210S763000, C210S903000
Reexamination Certificate
active
06419837
ABSTRACT:
BACKGROUND OF THE INVENTION
The US EPA currently restricts the total nitrate plus nitrite concentration (as nitrogen) in drinking water to less than 10 mg/L, and has reported that exposure to perchlorate should not exceed the 4-18 &mgr;g/L range in order to provide an adequate health protection margin. High nitrate
itrite and perchlorate levels in drinking water have been linked to serious health problems and sometimes death. The concern over nitrate
itrite has been driven by increasing levels of these contaminants being detected in drinking water supplies originating from both inorganic and biological sources. Inorganic sources include intense agricultural practices which contribute both ammonium and potassium nitrate fertilizers, explosives and blasting agents, heat transfer salts, glass and ceramics manufacture, matches, and fireworks. Biologically derived organonitrogen compounds are converted to nitrate in natural waters relatively rapidly. The main source for compounds is human sewage and livestock manure, which are not effectively removed by current treatment systems. Once in the environment, nitrates move rapidly into ground water reservoirs which supply drinking water. Recent studies have indicated the presence of perchlorate in drinking water wells throughout the Western United States. Perchlorate contamination of ground and surface waters originates from the manufacture and destruction of ammonium perchlorate; a strong oxidant used in the aerospace, munitions, and fireworks industries. Practical and efficient methods to treat water contaminated by these pollutants do not currently exist and are needed to insure a safe drinking water supply.
Ammonium perchlorate has been widely used by the aerospace, munitions, and fireworks industries, resulting in widespread soil and water contamination. The end of the Cold War has left the Department of Defense (DOD) with approximately 140 million pounds of ammonium perchlorate to be disposed of between 1993 and 2005. Perchlorate contamination in drinking water wells was first detected in early 1997 in northern California. These findings prompted further investigation, and perchlorate was detected in southern California wells, the Colorado River, Las Vegas wells, and Lake Mead. Although Federal drinking water standards do not currently exist for perchlorate, it has been placed on the current Drinking Water Contaminant Candidate List by the EPA.
1
There is significant concern over the human health effects of perchlorate due to its known interference with the thyroid gland's ability to utilize iodine and produce thyroid hormones. As a result of these findings, the California Department of Health Services (DHS) adopted an action level for perchlorate in drinking water of 18 &mgr;g/L.
2
This level was based upon an earlier recommendation by the EPA for a provisional reference dose (RfD) of 14 mg/kg/day.
3,4
In August of 1997, DHS notified drinking water utilities of their intent to treat perchlorate as an unregulated contaminant that must be monitored and reported to the DHS.
Perchlorate contamination has been detected in eastern Sacramento County at Aeroj et General Corporation's facility, a site previously owned by McDonnnell-Douglas, and a site previously owned by Purity Oil Company. Due to the presence of volatile organic chemicals (VOCs), contaminated groundwater at the Aerojet General site was treated and then reinjected into aquifers in the area. Monitoring of the reinjected water indicated that it contained up to 8000 &mgr;g/L of perchlorate. In February 1997, perchlorate was detected in drinking water wells in the Rancho Cordova area at levels as high as 280 &mgr;g/L. In July of 1997, DHS tested 62 wells in northern California, and detected perchlorate in 13. Of the 13, eight exceeded the 18 &mgr;g/L action level. Also, groundwater monitoring wells associated with the United Technologies Corporation in Santa Clara County yielded perchlorate concentrations as high as 180,000 &mgr;g/L, although no contamination of the drinking water systems was evident.
In southern California, perchlorate contamination has been detected in wells at Loma Linda and Redlands (5-216 &mgr;g/L) associated with past operations of the Lockheed Propulsion Company. Perchlorate was also detected at low levels in wells at Riverside, Chino, Colton, Cucamonga, and Rialto. In Los Angeles County, perchlorate has been detected in concentrations ranging from 4 to 159 &mgr;g/L in the areas of Azusa, Baldwin Park, Irwindale, La Canada, Flintridge, La Puente, Newhall, Pasadena, Santa Clarita, and West Covina. The perchlorate contamination was thought to originate from Aerojet (Azusa), the Azusa landfill, the Whittaker-Bernite site (Santa Clarita), and two Superfund sites, the Jet Propulsion Laboratory (Pasadena) and the Baldwin Park Operable Unit.
Outside of California, perchlorate has been found at levels of 5 to 9 &mgr;g/L in the Colorado River. These findings prompted testing in Nevada. In August, Nevada sites were found to contain perchlorate levels of up to 13 &mgr;g/L in drinking water wells, 1700 &mgr;g/L in the Las Vegas Wash, and 165 &mgr;g/L in Lake Mead. Monitoring wells in areas of ammonium perchlorate manufacturing were then found to have levels of 630,000 to 3,700,000 &mgr;g/L. In Utah perchlorate was found at levels of 200 &mgr;g/L at a rocket motor manufacturing facility.
Potassium perchlorate's health effects were originally discovered due to its use in the 1950's to treat Graves' disease, an autoimmune disorder in which patients develop antibodies to the thyroid stimulating hormone (TSH) receptors in the thyroid resulting in hyperthyroidism. Perchlorate was found to displace iodine in the thyroid, causing a decrease in production of triiodothyronine (T3) and tetraiodothyronine (T4), two regulating hormones which control TSH production. This effect has been shown to be reversible, with the perchlorate eventually being expelled from the thyroid. A study by Stansbury and Wyngaarden
5
was performed on Graves' disease patients following a single dose of perchlorate. Studies by Godley and Stansbury, Crooks and Wayne, Morgans and Trotter, Hobson, Johnson and Moore, Fawcett and Clarke, Krevans et al., Gjemdal, and Barzilai and Sheinfeld followed perchlorate administration to Graves' disease patients for periods up to several weeks.
6-14
Only one case by Connell
15
reported long term treatment in one patient for 22 years. Doses of perchlorate in these studies ranged from <1 mg/kg/day
5
to >20 mg/kg/day
7
with the typical exposure being 6-14 mg/kg/day. The observable effects of perchlorate include blocking of iodine uptake and discharge by the thyroid,
5
gastrointestinal irritation and skin rash,
6,7
and hematological effects including agranulocytosis and lymphadenopathy.
7,8
Seven cases of fatal aplastic anemia were reported at the same dose level, 6-14 mg/kg/day, at which other side effects occurred.
9-14
Following these early studies, the effects of perchlorate exposure on healthy volunteers were studied by Burgi et al.
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in five subjects for eight days at 9.7 mg/kg/day dosage levels. Brabant et al.
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studied five subjects dosed with 12 mg/kg/day of perchlorate for four weeks. Both of these studies observed effects on the thyroid at these levels. Studies in laboratory animals have included administration of perchlorate for four days by Mannisto et al.
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and for two years by Kessler and Krunkemper.
19
The animal studies only examined thyroid effects at dosage levels too high to evaluate the perchlorate level defined as the no observable adverse effects level (NOAEL).
The initial effort to establish a RfD for perchlorate was undertaken by the Perchlorate Study Group (PSG), a consortium of companies that use and/or manufacture perchlorates. The PSG submitted a provisional perchlorate RfD) to the EPA's National Center for Environmental Assessment Office (NCEAO) in 1995. The critical health effect cited in the PSG report was the interference with the thyroid functioning including the release
Hoey Betsey Morrison
Marger & Johnson & McCollom, P.C.
Umpqua Research Company
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